Conversion of hydrocarbon oils



May 16, 1939. J. G. ALTHER CONVERSION OF HYDROCARBON OILS Filed Nov. 30,1936 liw/wzfort' Ja /1 Gilt/Mr ,y lee Patented May 16, 1939 UNITEDSTATES PATENT OFFICE CONVERSION OF HYDROCARBON OILS Application November30, 1936, Serial No. 113,429

7 Claims.

This is a continuation in part of my co-pending application Serial No.355,704, filed April 17, 1929, now Patent No. 2,091,261.

This invention relates to improvements in a process for hydrocarbon oilconversion and refers more particularly to improvements designed for theefiicient cracking of hydrocarbon oils to convert and produce therefromproducts having higher commercial value.

The utility of the invention as well as many objects and advantagesthereof will be brought out in the following description.

The principal object of the invention is to subject hydrocarbon oil tosuch conditions of temperature and pressure as to produce maximum yieldsof low-boiling products suitable for use as motor fuel with a relativelysmall production of coke and gas.

Another object is to provide, in a cracking process and apparatus, stepsand means whereby it is possible to approach dry distillation.

Another object is to carry out the operation in such manner as to causethe non-vaporous residue or coke to accumulate in a low pressure zone.

Another object is to provide for lowering the reflux ratio by making itpossible to convert a greater proportion of the charging stock per passthrough the system. This is of particular importance in effecting thecapacity and thermal efficiency of the process.

In one type of operation practised commercially on a large scale, theconditions of operation are so controlled as to mainly produce agasoline-like product suitable for use as motor fuel, which is thedesired product of conversion, and a substantially solid coke-likeresidue. Such operation is commonly called the non-residuum type ofoperation, the expression residuum in such instance meaning liquidresidue. The operation is carried out in a tube and chamber type ofapparatus wherein the oil is heated to cracking temperature atsuperatmospheric pressure in the tube bank or cracking coil anddischarged into a chamber, also operated at substantial superatmosphericpressure, wherein conversion continues and separation takes placebetween the light and heavier reaction products, the latterbeing'reduced to coke in the chamber.

In a conventional non-residuum type of operation it is possible toapproach dry distillation in the chamber leaving only a coke-likeresidue of low volatility due, in part, to the large amount of timegiven to the heavy material in the chamber under the high temperatureand high pressure conditions maintained therein, whereby cracking,polymerization and distillation proceed simultaneously and reduction ofthe residue to substantially dry coke is accomplished. This could,obviously, not be done if it were not for the fact that a large amountof heat is constantly supplied to the drum by the incoming oil to carryon the reactions.

As is now well known, due to the polymerizing and cracking reactionswhich occur under the conditions maintained in the coking zone, theconventional non-residuum type of operation produces a high yield ofcoke, decreasing the actual onstream time and the yield of lighter, moredesirable products. To obviate this disadvantage and still obtain fairlyhigh yields of motor fuel, the liquid conversion products from the highpressure reaction chamber of a cracking system are now often flashdistilled in a separate unheated zone, operated at substantially reducedpressure and commonly termed a flash chamber, wherefrom the heavy liquidresidue which remains unvaporized by the flash distillation isrecovered. A flashing operation of this type has advantages as well asdisadvantages, one of the advantages being a long time onstream beforeshutting down due to the relatively small amount of coke formation andthe production of liquid residue, which is continuously removed from thesystem. Some of the disadvantages are a somewhat decreased gasolineyield, as compared with a non-residuum operation, and a relatively highyield of liquid residue or fuel oil, which is, of course, not asvaluable as gasoline and may not find a ready market.

In the non-residuum type of operation, there stantially all of thedesirable volatile matter is removed from the chamber through the vaporline and what remains in the chamber is substantially a solid. Theflashing operation is different-a relatively lower percentage of the oilleaving the pressure chamber leaves that zone through the vapor line inthe form of vapors and an additional quantity of desirable low-boilingproducts is withdrawn with the heavier oil from the bottom of thepressure chamber and discharged into the reduced pressure flash chamberwhere,due to the pressure reduction, latent heat is liberated from theoil and utilized to carry on vaporization of the desirable low-boilingfrac tions with a minimum of cracking and polymerization in the reducedpressure zone.

From the foregoing it will be apparent that there is a distillation(involving cracking and polymerization) in the pressure chamber and a ispractically a complete distillation, that is, subsecond distillation(Without substantial cracking and polymerization) in the reducedpressure flash chamber". Obviously the liquid residue recovered from theflash distilling operation will contain vapcrizable components which, inthe non-residuum type of operation are subjected to further cracking forthe production of additional yields of gasoline and, whereas thenonresiduum operation involves excessive cracking and polymerization inthe high pressure chamber, resulting in the excessive production ofcoke, the flashing operation produces higher yields of residual productsat the expense of the more valuable light distillate product.

The purpose of the present invention is to embody, in an eflicientprocess, the desirable features of the non-residuum and flashing typesof operation, the conditions being so controlled in the flash chamber asto produce a lower yield of substantially dry coke as compared with thenon-residuum type of operation and a higher yield of low-boilingmaterial, such as gasoline, the yield of the latter being even higher,in most cases than that produced in the non-residuum operation.

Another purpose of the invention resides in the employment of means toincrease the decomposition of both the vapors and liquid from thepressure chamber under independently controlled conditions designed toaccomplish the best results. This feature not only has the effect ofincreasing the yields of lighter hydrocarbons obtained from theoperation but also improves their quality, especially for use asgasoline, in that they are of higher anti-knock value.

The pressures on the high pressure reaction chamber may be substantiallythat of the coil outlet or lower, but in the preferable operation thispressure should be as high as possible, without substantial cokeformation in this zone, in order to increase the capacity of the unitand raise the thermal efliciency of the process.

Briefly, the process of the present invention is as follows:

The charging stock plus reflux will be pumped through a furnace having aheating coil from which the heated oil may be transferred to a highpressure reaction chamber. This chamber may be unheated but laggedagainst excessive radiation losses. vaporization and cracking takesplace in the chamber, from which vapors may be withdrawn separately fromthe liquid products and passed to a fractionator or,preferab1y through avapor heating coil wherein they are further cracked and then into a zoneof lower pressure into which residual oil from the reaction chamber willbe directed. In certain operations, either when the vapors are notsubjected to further cracking or are not supplied to the low pressurechamber, and/ or when additional cracking of the liquid residue isdesired, additional heat may be supplied to the latter before it entersthe low pressure chamber. In any case the liquid residue from thereaction chamber is supplied with additional heat within or prior to itsintroduction into the low pressure chamber for the purpose of effectingits reduction to coke in this zone.

From this point on the usual operation takes place, i. e., all thevapors from the flashing still are directed to a fractionator whereintheir sufficiently converted fractions are separated from theirinsufiiciently converted fractions or heavy ends, which latter arecondensed as reflux condensate by contact in the fractionator withincoming cold raw oil or other cooling medium,

said reflux being returned to the cracking coil for retreatment.

From the foregoing it will be appreciated that one of the fundamentalsof the invention requires that coke or carbon formed in producing amaximum yield of gasoline is formed outside of the pressure zone.

In order to more clearly understand the invention, I have shown theaccompanying drawing, which is a diagrammatic View, but not to scale, ofan apparatus suitable for carrying out the invention.

Referring to the drawing and to the operation of the process, oil to betreated is directed through line I and valve 3 into heating coil llocated in a furnace 5.

In heating coil 4 the oil is heated to a temperature within the crackingrange under a suitable pressure. The amount of oil passed through thecoil per unit time and the size of the apparatus are so correlated that,under the temperature and pressure used, the degree of cracking obtainedin the heating coil is preferably short of that at which substantialformation of coke and sludge-like matter occurs.

The heated oil is directed from coil 4 through line 8 and valve 9 intochamber ll].

Chamber Ii] may take any desired form and size in relation to thecapacity of the apparatus. It may be unheated and insulated against lossof heat by radiation or it may be heated, by well known means notillustrated, for the purpose of maintaining the material in chamber II]at the proper temperature, preferably not substantially higher than thetemperature at which the oil is discharged from heating coil 4.

While, for the treatment of most oils, it may be desirable not to raisethe temperature of the materials entering chamber It] to a temperaturesubstantially higher than that prevailing at the discharge of theheating coil 4, this is not to be taken as a limitation, since chargingstocks, particularly the lighter ones, may be heated in chamber H] to atemperature above that prevailing at the discharge of coil 4. On theother hand, particularly for the heavier charging stocks and dependingupon the limitations imposed upon the amount of coke and sludge to beformed or contained in the products, it may be desirable to maintain thematerials in chamber In at a lower temperature and/or pressure than thatreached at the discharge of heating coil 4 to decrease the rate at whichthe reaction proceeds in chamber Ii). To this end chamber I8 may beunheated or the oil may be cooled in a manner hereinafter described.

The vapors pass out of chamber it) through line I!) having valve 20 tofractionator 2|. As a feature of the invention I may subject all or partof the vapors removed from chamber to additional heating at elevatedtemperature to effect a controlled degree of so-called vapor-phasecracking whereby I am enabled to produce lighter valuable distillateshaving the characteristics of motor fuels or gasoline, possessing highantiknock properties due to the presence of controlled proportions ofaromatic and unsaturated hydrocarbons formed by said vapor cracking.

For this purpose a vapor coil 22 may be positioned in furnace 5 andlocated therein in such a manner that the combustion gases pass overcoil 22 before passing over coil 4. In this manner and because thecombustion gases passing over coil 22 are at a higher temperature thanwhen they pass over coil 4, a greater degree of radiant heat may beutilized in coil 22 than in cont: Coil 22 may be connected to vapor linel9 throughbr'anches 23 and 24, controlled respectively by valves 25 and26. By proper regulationof va'lves'ZO, 25 and'26, any desiredamount orvapors separated in chamber In may be passed through the'vapor' heatingcoil 22.

Referring now to the fractionator 2|, the vapors remaining uncondensedtherein leave the upper part thereof through line 21, having valve 28,through condenser 29 and thence to receiver 30. Receiver 30 is providedwith the usual gas release line 3|, having valve 32, and distillaterelease line 33, having valve 34. A' portion of the distillate collectedin receiver 30 may be returned, by well known means not illustrated, tothe upper portion'offractionator 2|, to serve as a cooling and refluxingmedium in this zone.

Provision is made for diverting regulated quantitles of the vapors fromline I9 through line It!) and valve IOI and introducing the same intochamber 54, by m ans of valves 51, eitherabove or below the' liquidlevel maintained therein. If full advantage of the partial pressureeffect of these vapors and their heat content is to be obtained theyshould enter chamber 54 at a relatively low point therein and passupwardly through the material undergoing coking in this zone to increasevaporization and assist the coking operation.

The reflux condensate formed in fr-actionator 2| may be withdrawn fromthe bottom thereof through line 39, in which may be interposed a hot oilpump 40 and valve 42, and through which said reflux condensate may bedirected to the main feed line whereby it may be returned forretreatment to the heating tubes 4 with a supply of fresh chargingstock.

Raw oil to be treated in the process may be drawn from suitable storagetanks (not shown) through line 43 and pump'44. From line 43 and bysuitable control of the valves shown, all or a portion of the raw oil tobe trfeated in the process may be diverted through line 45, having valve46, then to line4'l which connects with the main feed line I, wherebyall or a portion of the charging stock may be fed directly to theheating tubes 4, mixing before entering therein with reflux condensate,directed through line 39. Or, all or a portion of the raw oil may bediverted from line 43 through branch 48, having valve 49, and thenthrough line 50 from which it may be directed to the dephlegmator 2| tohelp fractionate the vapors therein. Raw oil fed to dephlegmator 2| isthereby preheated and mixed with reflux condensate and the mixture maybe directed to the heating coil 4, through lines 39 and I as heretoforedescribed. If desired, the line 511 may terminate in a closed coil (notshown) connected at its dischargeend tothe' feed lines 39 or 4'! insteadof mixing directly with the vapors. I have discovered thatw hen thedegree of conversion obtained in the cracking zone, such as heating coil4 and chamber I 0, is so controlled that the heavier liquidproductsseparated thereindo not contain more than, ordinarily, 5 percent andpreferably less than 2 percent, of sludge or coke-like materials, as maybe determined by so-called benzol centrifuge method, said heavier liquidproducts comprise a substantial proportionoffraotions, which, whenseparated from such solids or sludge like materials under properconditions, may be subjected advantageously to additional conversionforthe formation of substantial additional yields of motor fuel. Thismay be effected by regulating the conditions in coil 4an'd'ch-amberl0,or by subjecting the heavier liquidproducts withdrawn from chamber ID tosuch additional treatment, as will hereinafter be described, that aso-called dry distillation thereof is effected, leaving in the zone ofdistillation a substantially solid residue, the remaining fractionshaving been vaporized to produce a material which may be advantageouslysubjected to additional cracking.

The heavier liquid products are withdrawn preferably from the bottom ofchamber I0 through line 5| and may be directed through valves 52 and 53in this line into chamber 54.

I By means of the pressure reduction obtained by proper control ofvalves shown, a large portion of said unvaporized liquid products may bevaporized in Chamber 54. Depending upon the conditions under which theoperation is carried out and upon the charging stock used, suchreduction in pressure may be sufficient to distill or vaporize saidheavier liquid products substantiallyto dryness by means of theself-contained heat. However, I have found that generally thisself-contained heat is not sufficient and in a majority of cases it isnecessary to supply additional heat to the heavy liquid productswithdrawn from the reaction zone, before and/or during their flashdistillation, in order to obtain vaporization thereof to substantialdryness.

Accordingly one of the features of the invention of this application, asdistinguished from my companion applications, Serial Nos. 113,427,113,428 and 113,430, filed on even date herewith provides for directingany desired portion or all of the" heavier liquid products withdrawnfrom the reaction having valves a heating coil zone It! through branchlines 55, 56 interposed therein, and through 58 located in furnace 5.

It is desirable to regulate theheating of the heavier liquid products ofreaction in such a manner that, while they receive the necessaryadditional heat to cause substantially dry distillation by simultaneousor subsequent reduction of pressure, at the same time the additionalheat treatment to which such products are subjected does not causesufficient additional cracking thereof to effect the formation of anexcessive amount of sludge or coke-like constituents in the heatingcoil.

Therefore, the heating coil 58, in which the heavier products ofreaction receive additional heat, may be located in furnace 5, at such apoint that rapid heat transfer takes place, so that the amount of heatrequired may be transmitted'to the heavier liquid products of reactionin the shortest possible time. In this manner I materially decrease theadditional cracking and polymerization to which such products aresubjected in the heating coil as compared with that obtained with lowerrates of heating and more prolonged time in this zone. For this purposeI have shown, in the drawing, the heating coil 58 positioned near thehottest part of furnace 5, whereby, With the help of intense radiantheat and high temperature combustion gases and nonvaporized productswithdrawn from chamber ll! may be raised rapidly to the requiredtemperature.

The sizes of heating coil 58 must be carefully "proportioned relative tothe amount of materials to be fed therethrough and the degree of heattransfer employed therein. To assist in theregulatiQn oi the heattransfer in heating coil 4, vapor coil 22 and coil 58 respectively,

which may be more or less independent of each other, I may providefurnace 5 with such means as are well known to regulate the temperatureand the amount of combustion gases therein. Such means are, forinstance, flue gas recirculation, superheated steam injection andadditional burners properly located in furnace 5. Such additional meanshave not been shown on the attached drawing, as I believe they are wellknown and would simply complicate the drawing.

By the proper control of the degree of reaction obtained in the zones 4and I0 and by proper control of valves 52 and 56, as well as by thecontrol of the heat transfer to coil 58 more or less independently ofthe heat transfer to the other coils shown, as heretofore explained, anydesired additional amount of heat may be given to the heavier liquidproducts withdrawn from chamber In in the shortest possible time. Inthis manner, and coupled with proper control of the degree of reductionof pressure to which said heavier liquid products may be subjected bymeans of either valves 52, 56 or 53, substantially dry distillation ofsaid heavier liquid products is effected in chamber 54 withoutexcessively increasing the comparative amount of coke formed in theprocess. Coke formed in the operation of the process and deposited inchamber 54 may be removed therefrom through top or bottom manholes inthe usual manner (not illustrated) One of the principal features of thisinvention resides in depositing the bulk of the carbon or coke outsidethe zone of high pressure. This permits the use of much cheaperequipment and minimizes the danger of explosion.

It is to be understood that the preferred method of operation is of thelow level type, wherein a minimum quantity of residual oil is maintainedin chamber 10. That is, residual oil is withdrawn from chamber 10 beforeit has had sufficient time to form more than 5 percent or thereabouts ofsludge or coke-like constituents.

Vapors separated in chamber 54 may be removed therefrom through line 66having valve 61 wherefrom they may be passed, by well known means notillustrated, directly to condensing and collecting means of well knownform, not shown, and may thence be removed from the process or returned,in part, to the heating zone for retreatment. However, as shown in thedrawing, the Vapors from chamber 54 are preferably supplied tofractionator 69, wherein they are subjected to controlled partialcondensation by introducing a suitable cooling medium into this zonethrough line 10 having valve 1|; or raw oil to be charged to the processmay be diverted from line 43 through line 12, having valve 13, andintroduced into column 69 to assist cooling and fractionation therein.

Vapors uncondensed in column 69 may be removed therefrom through upperdraw-off line 14, having valve 15, and passed through condenser 16 toreceiver 11 which has the usual gas release valve 18 and distillaterelease valve 19.

The fractions of the vapors condensed in column 69, comprising refluxcondensate, may be discharged from the bottom thereof through line 89,in which may be interposed pump 8|. Thence, they may be diverted throughbranch 82 having valve 83, which connects with line 58, whereby saidfractions may be returned via fractionator 2| to further cracking incoil 4. Or, the fractions condensed in tower 59 may be passed throughbranch 84, having valve 85, connected with feed line 41, whereby saidfractions may be returned directly to heating coil 4.

It will be apparent from the drawing that by suitable control of valves13, 49, 46, 85 and 83, any desired proportion of fresh raw oil or ofmaterials withdrawn from the bottom of tower 69, independently of eachother, or together, may be directed to dephlegmator 21 or to the heatingcoil 4.

It may be desirable to control the degrees of reaction taking place inheating coil 4, chamber l8 and vapor coil 22, respectively, bycontrolling the temperature, characteristics and quantity of thematerial passing through these respective zones. For instance it may bedesirable to introduce into the stream of heated products passing fromheating coil 4 to chamber 10 a regulated portion or all of thehydrocarbon oil charging stock for the process or liquid products suchas condensates from other parts of the system. It may be desirable tointroduce one or more various oils such as charging stock and/or refluxcondensate from iractionator 2| or fractionator 69 into the stream ofvaporous products passing from chamber IE) to heating coil 22. Toaccomplish this, oil, comprising either reflux condensate fromfractionator 69 or charging stock from line 43 or a mix ture of the two,may be diverted from line 41 through line 98 and valve 98' into line l9,while oil from line 39, comprising either reflux condensate fromfractionator 2! or a mixture of the same with charging stock supplied tothis zone, may be diverted through line 88 and valve 89 into line 80 andintroduced into line I6. In a similar manner oil from line 39 may bedirected through valve 86 and line 81 into line 3 or oil from line 4"!may be directed through line 86' and valve 81' into line 86 and thenceinto line 8.

While I have diagrammatically indicated in the drawing specific types ofconstruction for the various parts of the apparatus, it is to beunderstood that other forms of apparatus and other types of constructionmay be used for such parts. For instance, a vapor-phase crackingchamber, suitably heated, may be substituted for the vapor heating coil22. A so-called soaking coil or digestion chamber may be substituted forchamber 50, preferably with a separating chamber following the soakingcoil or digestion chamber. As another modification it may be desirableto interpose a separator in the discharge line from vapor heating coil22 or its equivalent, whereby heavy liquid products of polymerizationand cracking formed in coil 22 may be separated from the vapors beforeintroducing the latter into fractionator 2 I.

While I have illustrated a specific arrangement of the various heatingcoils of the process and a specific construction for furnace 5 it isentirely within the scope of the invention to use other arrangements ofthese parts providing that such alternative arrangements permitoperation of the process for the purpose and with the desired resultsheretofore mentioned. For example, each of the heating coils 4, 22 and58 may be disposed in separate furnaces or independently heated zones ofthe same furnace, in which case the furnace or heating zone in whichcoil 22 and coil 58 are located are preferably of such type as willpermit the use of rapid heat transfer rates such as caused by the use ofintense radiant heat. On the other hand heating zones 4, 22 and 58 ortheir equivalents may be positioned in separate heating chamberswherein, in addition to or independently aiisaii of heat which may beproduced by burners, the products of combustion which leave the heatingzonesmaintained at relatively high temperatures may be utilized as apart or all of the heating medium for the zones maintained at lowertemperatures.

As an illustration of the temperature and pressure conditions which maybe employed in an apparatus such as illustrated to accomplish thedesired results, the oil supplied to heating coil 4 may be subjected toa temperature, measured at the outlet from this zone, of from 850 to 960F; or thereabouts, preferably at a superatmospheric pressureof from 100to 500 pounds, or more, per square inch. Substantially the same orsomewhat lower temperatures and/or pressure conditions may be maintainedin chamber l and the materials supplied to heating coil 22 may beheated, for example, to a temperature of from 950 to 1100 F., orthereabouts, at substantially the same or lower pressure than thatmaintained in chamber Ill. The heavy liquid products removed fromchamber ID may be passed through coil 58 and quickly heated to atemperature ranging, for example, from 925 to 1050 F. and thenceintroduced into chamber 3, without allowing the oil suflicient time inthe heating coil and communieating lines to permit any substantialformation and deposition of coke therein. The pressure maintained at theoutlet from heating coil 58 may range from substantially the same asthat employed in chamber l0 down to substantially atmospheric or a lowsuperatmospheric pressure of, for example, 25 pounds, or thereabouts,per square inch. The pressure maintained in chamber 5 may besubstantially the same or somewhat lower than that employed at theoutlet from heating coil 58 and preferably is substantially lower thanthe pressure maintained in chamber Ill. The fractionating, condensingand collecting portions of the system may employ pressures substantiallythe same or somewhat lower than the pressure employed in the precedingequipment.

As a specific example of an operation of the process as it may beconducted in an apparatus such as illustrated and above described, thecharging stock, which is a Mid-continent topped crude of approximately25 A. P. I. gravity, is supplied, together with reflux condensate fromfractionator 69, to heating coil l from which the heated products aredischarged into chamber II! at a temperature of approximately 940 F. andat a superatmospheric pressure of approximately 500 pounds per squareinch. Chamber l0 and heating coil 22 are maintained at approximatelythis same pressure. Vaporous and liquid conversion products areseparately Withdrawn from chamber ill, the vapors passing throughheating coil 22 wherein they are maintained at a substantially'uniformtemperature of approximately 975 F. While the liquid products arequickly heated in coil 58 to a temperature of approximately 950 F. at asuperatmospheric pressure of about 75 pounds per square inch, the heatedproducts from coil 58 being introduced into the upper portion of chamber54 and the heated products from coil 22 being introduced into the lowerportion of this zone. Chamber 56 is maintained at a superatmosphericpressure of approximately 50 pounds per square inch and the residualproduct produced in this zone is substantially dry coke. Vaporousproducts from chamber 54 are subjected to fractionation in iractionator69 wherefrom reflux condensate is returned to heating coil 4 while theoverhead vaporous products from fractionator 69,

5 comprising distillate of good antiknock value within the, boilingrange of gasoline and gaseous products of theprocess, ,are passedthrough condenser 16 into receiver 17 wherefrom the distillate anduncondensed gases are separately recovered.

The above described operation will yield, per lprarrel of chargingstock, approximately 65 percent of,400 F. end-point gasoline having anoctane number, by the motor method, of approximately 72 andapproximately '70 pounds of low volatile coke, suitable for sale asdomestic fuel, the remainder being chargeable principally touncondensable gas. v

I claim as my invention:

1 A process for the pyrolytic conversion of hydrocarbon oils whichcomprises cracking an oil at elevated temperature and substantialsuperatriiospheric pressure in a heating coil and comniiihicatingenlarged reaction chamber, separately r'e'rrio'ving resultant vaporousand liquid conversion products from the reaction chamber, quick- 1yreheating said liquid conversion products separately'iwithdrawn from thereaction chamber to a sufll ci'ently high temperature, in a separateheatmg coil, to inducetheir subsequentreduction to coke, introducing thereheatedmaterialsiinto a coking zone operated at substantially reducedpressure relative to that employed in thereaction chamber wherein theirreduction to coke is eff'e'cted, independentlyheating vaporous productsremoved from the reaction chamber to vapor phase cracking temperatureand then introducing thes'ame to the coking zone to assist the cokingoperation, removing vaporous products from the coking zone andsubjecting the same to said fracticnation subjecting fractionated vaporsof the desired boiling point to condensation, recovering and separatingthe resulting distillate and gas iiidreturhihg reflux condensate formedby said fractionation, to .the for, further cracking. 25A process forthe pyrolytic conversion of hydrocarbon oils which comprises subjectingan oil to cracking conditions of elevated temperature the products,separately subjecting said vaporous and liquid products each toadditional independently controlled cracking conditionsv of temperatureand pressure, commingling heated products from both of the lastmentioned heating operations and reducing their non-vaporous residualcomponents o coke, subjecting the vaporous components of the commingledproducts to fractionation for the formation of reflux condensate,subjecting fractionated vapors of the desired endboiling point,comprising materials of good antiknock value within the boiling range ofgasoline, to condensation and recovering the resulting distillate.

3. A process for the pyrolytic conversion of hydrocarbon coils whichcomprises subjecting an oil to cracking conditions of elevatedtemperature and superatmosp-heric pressure, separating the resultantvaporous and liquid conversion products, separately subjecting saidvaporous and liquid products each to additional independently controlledcracking conditions of temperature and pressure, commingling heatedproducts of both of the last mentioned heating operations and reducingtheir non-vaporous residual components to coke, subjecting the vaporouscomponents of the commin-gled products to fractionation for theformation of reflux condensate, returning reflux condensate formed bysaid fractionation to the first-mentioned heating coil first mentionedcracking step, subjecting fractionated vapors of the desired end-boilingpoint, comprising materials of good antiknock value within the boilingrange of gasoline, to condensation and recovering the resultingdistillate.

4. A process for the pyrolytic conversion of hydrocarbon oils whichcomprises subjecting hydrocarbon oil charging stock to conversionconditions of cracking temperature and substantial superatmosphericpressure in a heating coil and communicating enlarged reaction chamber,separately removing resultantvaporous and liquid conversion productsfrom the reaction chamber, subjecting liquid products thus withdrawnfrom the reaction chamber to additional heating in a separate heatingcoil, introducing the heated oil from said separate heating coil into acoking zone, subjecting vaporous products Withdrawn from said reactionchamber to additional cracking in another separate heating coil,introducing heated products discharged from the last mentioned heatingcoil into the coking zone wherein they commingle with the residualmaterials supplied thereto and assist their reduction to coke, removingvaporous products from the coking zone and subjecting the same tofractionation for the formation of reflux condensate, subjectingfractionated vapors of the desired end-boiling point to condensation andrecovering the resulting distillate comprising materials of goodantiknock value within the boiling range of gasoline.

5. A conversion process which comprises subjecting hydrocarbon oil tocracking conditions of temperature and pressure in a heating coil andseparating resultant products into vapors and unvaporized oil in anenlarged chamber, removing unvaporized oil from the chamber and heatingthe same to cracking temperature under pressure in a second heating coiland then distilling the same to coke in a second chamber, separatelyremoving vapors from the first-named chamber and heating the same tovapor phase cracking temperature independently of the first-mentionedoil and said unvaporized oil, discharging heated products of thelast-mentioned heating step into the second chamber to assist the cokingoperation therein, removing vapors from the second chamber andfractionating and condensing the same.

6. In the conversion of hydrocarbon oil wherein the oil is cracked underpressure in a cracking zone and hydrocarbon vapors and residual liquidseparately withdrawn from said zone, the method which comprises passingthe residual liquid through a heating coil and heating the same thereinto cracking temperature under pressure, discharging the heated productsfrom said coil into a reduced pressue coking zone and reducing the sameto coke therein, passing hydrocarbons removed as vapor from the crackingzone through a separate heating coil and therein heating the same tohigher temperature than the oil in the cracking zone and the first-namedcoil, discharging heated products from said separate coil into thecoking zone to assist the coking operation therein, removing vapors fromthe coking zone and iractionating and condensing the same.

7. A conversion process Which comprises heating hydrocarbon oil in aheating coil sufliciently to vaporize a substantial portion thereof andseparating the same into vapors and unvaporized oil in an enlargedchamber, removing unvaporized oil from the chamber and heating the sameto cracking temperature under pressure in a second heating coil and thendistilling the same to coke in a second chamber, separately removingvapors from the first-named chamber and heating the same to vapor phasecracking temperature independently of the first-mentioned oil and saidunvaporized oil, discharging heated products of the last-mentionedheating step into the second chamber to assist the coking operationtherein, removing vapors from the second chamber and fractionating andcondensing the same.

JOSEPH G. ALTHER.

